This invention relates to a fuel pump assembly, and more particularly to a multi-pivoting float-type fuel level sensor of the fuel pump assembly.
A fuel pump assembly for a liquid fuel tank of a vehicle is known to have a flange mounted sealably to a wall of the tank with an electric fuel pump of the assembly carried by the flange and disposed in the interior of tank. The fuel pump has a fuel inlet typically extending from a fuel filter, and a fuel outlet which is typically a tube or fuel resistant hose connected to a fitting extending through the flange to supply fuel to the vehicle engine. A connector for electrical wires also projects through the flange to provide electrical power to the pump and send a fuel level signal from the sensor to a remote fuel level indicator.
The wall of the fuel tank has a peripheral edge which defines an access hole through which the fuel pump assembly projects into the tank. An O-ring, or any variety of fuel resistant gaskets or seals are typically compressed between a circumferential shoulder of the flange and the peripheral edge of the tank wall to prevent fuel leakage and fuel vapor permeation egress from the tank. To control manufacturing costs, preserve the structural integrity of the tank, and minimize any opportunity of seal failure, the access hole is substantially round and minimal in diameter, yet, large enough to permit insertion of the fuel pump assembly into the tank.
The fuel pump and any variety of structures which attach, support, and/or communicate the pump with the flange are typically elongated and compact in design having a centerline which is generally parallel to a centerline of the access hole during insertion of the fuel pump assembly into the fuel tank. Unfortunately, other components of the fuel pump assembly which substantially project laterally from the pump centerline obstruct insertion of the full assembly through the small access hole, thus laterally projecting components of the pump assembly must be assembled to the remainder of the assembly inside the tank.
One such component of the fuel pump assembly is a fuel level sensor with a wiper-arm type float mechanism which typically has an elongated wiper arm engaged pivotally connected to a carrier of a resistor card at one end and engaged to a float at an opposite distal end. The float is buoyant upon the surface of the liquid fuel contained within the tank so that as the fuel level varies, the resultant change in float elevation causes an electrical contact engaged to the wiper arm to pivot or sweep across a series of electrical contacts of a variable resistor rigidly attached to the pump. The wiper arm projects generally laterally from the fuel pump. This is particularly true for fuel tank applications where the pump centerline descends into the tank at an angle projecting away from the downward sweep of the wiper arm. The length of the wiper arm is dictated by the changing fuel surface elevation range (i.e. between a full and an empty tank of fuel).
Unfortunately, the substantial length or lateral projection of the wiper arm from the pump centerline obstructs insertion of a fully pre-assembled fuel level sensor and pump assembly into the tank through the small access hole. Thus, either the wiper arm must be assembled to the fuel pump bracket after the pump is inserted into the tank, which leads to greater manpower and expense during manufacturing, or the access hole must be enlarged beyond a desirable size which leads to a weakening of the tank structure, a greater potential of fuel leakage and/or permeation egress through the seal, and greater material and manufacturing costs.
A fuel level sensor and pump assembly inserts through an access hole of a fuel tank so that an elongated fuel pump is disposed preferably generally vertically and completely within the fuel tank, and so that a flange of the assembly is engaged sealably to the wall of the fuel tank about a peripheral edge which defines the access hole. A multi-pivoting fuel level sensor mechanism generally projects laterally when in a biased operating position from the elongated fuel pump to a float at a distal end. During insertion of the fully pre-assembled fuel level sensor and pump assembly through the access hole of the fuel tank, the fuel level sensor mechanism is pivoted by an external force from the biased operating position to a collapsed position substantially parallel, and closely orientated, to the fuel pump. This temporary collapsed orientation permits insertion of the fuel level sensor and pump assembly through the relatively small access hole of the tank. After insertion, the external force is released and the fuel level mechanism pivots from the collapsed position back to the operating position.
A base of the fuel level sensor mechanism is pivotally carried by the fuel pump enabling movement between the operating and collapsed positions. An elongated wiper arm of the fuel level sensor mechanism by pivotally carried by the base and projects to a distal end which is preferably engaged pivotally to a float. The base carries a variable resistor which senses fuel level as the wiper arm is swept across a series of contacts of the resistor caused by the buoyant float in response to the varying fuel level. Preferably, the pivotal connection between the base and the fuel pump has a stationary pin which passes through an eyelet of the base and is attached to the fuel pump. A spring preferably coils about the pin and engages the fuel pump at one end and the base at the other end to resiliently bias the fuel level sensor mechanism into its operating position.
Objects, features and advantages of this invention include a fully pre-assembled fuel level sensor and pump assembly that can be inserted into a fuel tank through a relatively small access hole. Other advantages are a structurally strong fuel tank, superior sealing of the access hole of the tank, simplified overall assembly of the fuel level sensor, pump and tank, reduced manufacturing costs, and an overall cost effective, robust, and low maintenance design.